Radiator Identification/Overheating Issue
 

Hey everyone, first time here, so bear with me if I breach etiquette.

I'm trying to resolve a long-standing issue on my dad's '65 restoration. The original resto was done by Dallas Mustang (apparently they recently shut down, though the website is still up). They performed a full restoration on the car. I've managed to hammer out the remaining persistent problems, but she has an issue with running hot. When I get her to highway speed (usually 60+ mph) for more than about 10 minutes, the temp gauge will creep up to near-max, though it'll never actually boil over. I drove her from Tulsa to Austin, and it ran hot the entire way, but no weird behavior otherwise.

I don't have documentation on what radiator is installed, but the DM website only shows one compatible radiator for the 65. Cross-referencing the mfg part number points to a Scott Drake, and this one looks identical to the one installed. The only marking is "CC259E 5728" stamped in the metal on the side. Prior to me jumping into the fray, they'd tried four t-stats and two different radiators. Hoses are all good, and there are no leaks. Also, the fan installed is something retarded powerful (I'll have to look at the mfg label on it), is wired to be always on, and sounds like a damn F18 taking off.

Also, I feel this bears mentioning: he apparently had them bore the original 289 out to 302. No, I don't know what compelled him to do that, but now I'm doing damage control.

Anyway, thanks for any help.

Correction to my OP: The bored-out engine did an energetic disassembly during the restoration, so it has a bona-fide 302 in there now. However, the radiator in there is the one they used with the first engine, so that one may be one designed for the 289 vs the 302.

It runs just as hot at idle as it does on the freeway?
What kind of fan is it using?
Is the current radiator some kind of brass or is it aluminum? (the one in the link is aluminum so Im guessing this is the same)
Is it using a fan shroud?

No, it doesn't start getting hot until I get it up to around 60+ on the highway for 10-15 minutes. City driving (even extended periods) is fine, idling is fine.

The radiator is aluminum. Attached is a shot of the radiator and fan. There's a small label at top center on the fan, but there aren't any visible markings. I'm trying to get ahold of my dad to see if he remembers the make.

https://cimg8.ibsrv.net/gimg/mustang...eaed93766b.jpg

Just got a response back. The fan is a Spal. Not sure of the exact model, though.

Typically they run hotter sitting in traffic with larger variations in temp. I have a precise digital gauge that reads to the 10th of a degree I run a 190f T stat and in 100 deg weather i get around 200 in traffic and it. Initially it will be at 195 then creep up to about 203 then stabilize around 200.
on the freeway at 75ish Ill get 195 with a range of 195.2 to 195.6

So to have it keep the engine cool in traffic but not on the freeway makes me think its not a radiator issue. The spal is a good fan too although it sounds like it was poorly installed.

The real question now is....Is it actually overheating or is the gauge not accurate.

after driving it around use a non contact temp gun and read the temps on the T stat housing and the top rad hose (the rad its self is a poor choice due to reflectivity of metal) Take measurements from about 3" away and always the same distance when comparing temps.
What temps are we seeing.... drive it on the freeway when the gauge reads hot find an exit or something and try to take reading when the gauge indicating hot using the same method as before. whats the temp say then?

It could be a head gasket issue. you can buy a kit to check for exhaust gas in the rad coolant...but verify temps first.

180 warmed up is probably on the cool side
185 to 190 is near engineered specs
200 is okay but you would like to see less
212 is safe but would run better at 200
220 is tolerable upper limits and should be avoided extending running at these temps will noticeably shorten engine lifespan.
225 is shutdown point and should never be exceeded. there is an issue that must be solved
230 is risking immediate engine damage
235+ high risk of immediate engine damage

You could have a radiator hose collapsing that is reducing the flow at sustained higher RPM.s One or both of your radiator hoses should have a springs in them.

The other thoughts is gunk buildup in the radiator or a restricted flow.

P.S. even with an electric fan there should still be a fan shroud over the entire assembly. This directs /forces fresh air through the radiator and onto the motor as well since you no longer have a clutch fan to help draw the air over the engine.